The Ischemic Optic Neuropathy Decompression Trial (IONDT), the first multicenter, prospective randomized controlled trial of newly diagnosed patients with non-artertic anterior ischemic optic neuropathy (NAION), found that optic nerve decompression surgery (ONDS), when compared to careful foIlowup, is not effective and may be harmful to a patient's visual acuity. Randomized patients have been followed for 1 to 3 years (median = 1.51 years) since onset of symptoms. Patients with NAION whose vision was better than 20164 were not randomized to treatment but were followed as a natural history cohort for the same length of time. The goal of the IONDT Followup Study is to follow all patients enrolled in the IONDT to learn more about the natural history of NAION, specifically: incidence of NAION in the second eye; changes in visual acuity over time in the study and fellow eyes; incidence of systemic disease; health-related quality of life (QOL); medication use, including aspirin; and risk factors for ocular and systemic events occurring after enrollment. An additional goal of the Followup Study will be to analyze all visual fields and fundus photographs accumulated during the IONDT and IONDT Followup Study. IONDT patients will be followed at all 24 participating Clinical Centers an additional four years at annual visits related both to the effect of ONDS and the natural history of NAION. Examinations will consist of ophthalmic examinations, measurement of visual acuity and visual field. In the event of NAION occurring in the second eye, a special visit will be scheduled at the Clinical Center, which will be similar to annual visits with the addition of fundus photographs. At three month intervals between annual visits, a coordinator located at the Coordinating Center will telephone patients to maintain high rates of patient followup, ensure that annual visits take place, and determine whether any ophthalmic or medical events have occurred between annual visits.